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Previous: <a href="Accessing-the-wisdom-API-from-Fortran.html#Accessing-the-wisdom-API-from-Fortran" accesskey="p" rel="prev">Accessing the wisdom API from Fortran</a>, Up: <a href="Calling-FFTW-from-Modern-Fortran.html#Calling-FFTW-from-Modern-Fortran" accesskey="u" rel="up">Calling FFTW from Modern Fortran</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
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<a name="Defining-an-FFTW-module-1"></a>
<h3 class="section">7.7 Defining an FFTW module</h3>

<p>Rather than using the <code>include</code> statement to include the
<code>fftw3.f03</code> interface file in any subroutine where you want to
use FFTW, you might prefer to define an FFTW Fortran module.  FFTW
does not install itself as a module, primarily because
<code>fftw3.f03</code> can be shared between different Fortran compilers while
modules (in general) cannot.  However, it is trivial to define your
own FFTW module if you want.  Just create a file containing:
</p>
<div class="example">
<pre class="example">  module FFTW3
    use, intrinsic :: iso_c_binding
    include 'fftw3.f03'
  end module
</pre></div>

<p>Compile this file into a module as usual for your compiler (e.g. with
<code>gfortran -c</code> you will get a file <code>fftw3.mod</code>).  Now,
instead of <code>include 'fftw3.f03'</code>, whenever you want to use FFTW
routines you can just do:
</p>
<div class="example">
<pre class="example">  use FFTW3
</pre></div>

<p>as usual for Fortran modules.  (You still need to link to the FFTW
library, of course.)
</p>


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